coming to pay tribute to south africa, the father of modern south africa. the single largest gathering of heads of state in generations. among them president obama and three ex-presidents from the united states arriving this morning. former presidents clinton and carter flying separately along with presidents, prime ministers and princes and kings from nearly 100 countries. no less significantly ordinary people from all across south africa all converging on a soccer stadium here in johannesburg. it's built to hold 94,000 and may not be big enough and certainly too small to contain all the people to thank the man who led them to freedom. they led a country to freedom and showed the world a better way. i had the privilege of spending time with bono of the band u2. he knew nelson mandela over the years and been the voice for justice here since the late 1970s. when you first heard that he had died, what went through your mind? >> stubborn until the end. you know, it was like he was playing this big sort of, he was trying to outstare god. >> his leadership was,